According to me kaspersky internet security 2009 is nice antivirus. because:
It detect all types of threats (generally).but one problem is that, some time it detect the threat, but instead of neutralizing that threat it gives the option of skip, I don’t know why? But don’t worry, it will not harm the pc.
This is not so much heavy software; it will not consume your time while system start and turnoff. But it will slow your system while systems full scan.(generally all antivirus does)
It required regular internet for updates.
Always try to buy software from stores where you will get it in laser price then net. I purchase it for 700 RS for 3 computers. where as in net price is 1885 RS for 3pc. Thats all
Personally, I believe Norton is also a good product but you need more ram. And it makes your system slow.